Dyadic interactions, attachment and the presence of triadic interactions in chimpanzees and humans

•Strong similarities between human and chimpanzee infants are found in early dyadic social and object-based interactions.•Strong similarities between human and chimpanzee infants can be found in early triadic interactions.•Early experiences in emotional engagement have a major impact on social cognition outcomesor both humans and chimpanzees.

From a developmental perspective, dyadic interactions with social partners and dyadic interactions with objects underpin early social cognition in humans and chimpanzees. In humans, dyadic social relationships form in the first three months of life, dyadic relations with objects form in the first 6 months of life, and triadic relations begin around 8-12 months. In chimpanzees, a similar developmental pattern is evident with dyadic social relationships forming in the first three months of life, dyadic relations with objects forming in the first 5 months of life, and triadic relations in the latter half of the first year of life. During ontogeny humans and chimpanzees experience emotional engagements, both with social partners and with objects, and these impact outcomes in social cognition. Rather than being considered too complex, diversity of socio-emotional experiences during development can be embraced, with the goal to specify how they influence social cognition outcomes in humans and in chimpanzees. This process may provide the evolutionary and biological foundations for plasticity.